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  <title>Document</title>
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<style>
  div {
    width: 0;
    height: 0;
    border-top: 50px solid red;
    border-right: 50px solid transparent;
    /* border-right: 50px solid green; */
    /* border-bottom: 50px solid blue; */
    /* border-left: 50px solid orange; */
    border-left: 50px solid transparent;

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<body>
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